[Gllug] 'sigset' function

[Nix]

On Mon, 24 Mar 2003, t. clarke uttered the following:
> Hi
> I am converting some SCO software over to linux and one of the programs uses
> the sigset function.

OK.

> The program compiles and links, but with a warning about not casting a pointer
> from an integer. This appears to be due to a call along the lines of:
> a=sigset(......)  where a is defined as a pointer to a function.
> I assume that this error occurs because there is no prototype for sigset within
> the <signal.h> header file and the compiler accordingly assumes a default int
> return from the sigset function.

Yes, it exists --- but it's intentionally undocumented by the glibc
folks, because sigaction() is the preferred function; sigaction() lets
you specify what happens to the signal disposition when the signal
handler is invoked, and much else.

> I cannot find any manual page within the linux software (Redhat 7.1) that
> mentions sigset -

No, the *link* would fail.

The canonical reference is POSIX.1:

<http://www.opengroup.org/onlinepubs/007904975/functions/sigset.html>.

>                   but presumably the function actually exists otherwise the
> compile would fail completely !

It does. You aren't specifying what standard you're writing against, so glibc
assumes POSIX 1003.1c-1995, which does *not* include sigset() and friends.

You'll want to #define _XOPEN_SOURCE 500 (at least) for sigset().

(See `info libc Feature' and the top of /usr/include/features.h.)

>                                 I am reluctant to amend the code to use
> 'signal' as I understand this mechanism is unreliable. Sigaction gave me a few
> problems with SCO which is why I used sigset (simpler calling sequence anyway!).

Bleah, SCO. I'd autoconf up a test for whatever the SCO problem was and
work around it only on SCO, myself...

Anyway,

#define _XOPEN_SOURCE 500

should fix your immediate problems.

-- 
#ifdef USE_ISPTS_FLAG
		} else {	/* else pty, not pts */
#endif

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